How to capture partner details of PO before saving

Hi All,

Requirement is to get print preview of a PO before saving it.

I have a custom driver program and custom script for displaying preview after saving PO.

I have to add some validations based on partner functions on the screen before saving PO.

My question is how can i get partner functions of the PO before saving it.

Thanks & Regards,

Malvi Aggarwal